By 2010 the Earth had reached a remarkable milestone: one billion cars — or, to be precise, one billion motorized vehicles, including cars, trucks, buses, and motorcycles but excluding off-road vehicles such as tractors and bulldozers.

And if that figure isn’t jolting enough, by 2030 it’s projected that we will have double that number: 2 billion cars.

What will this mean for our planet, our health, our lifestyles, and our environment?

Traffic Jam

The exponential increase in vehicles is coinciding with the growth of megacities across the world, especially in developing nations. By 2030, more than half of the projected 9 billion people on Earth will live in cities.

If you think traffic jams are bad now, imagine what it’ll be like with another 2 billion people than we have today — increasingly crammed into cities and driving another 1 billion vehicles.

If you’ve ever visited a mega-city like Beijing or São Paulo or Jakarta, you’ll realize that traffic chaos is the norm, not the exception. And that’s even outside of rush hours.

And with more vehicles, traffic accidents will increase. The World Health Organization estimates that 1.25 million people are currently killed in vehicle accidents each year. For people ranging from 15 to 29 years of age, it is the number one cause of death.

By 2030, the number of fatalities is expected to rise to 1.8 million people per year. If vehicle-related mortality were considered a global epidemic, it’d be a more important killer than HIV-AIDS.

Greenhouse Gases

At the Paris climate conference, global leaders committed to limit global warming to 2 degrees C, with a stated aspiration to limit the increase to 1.5 degrees C. But it’s a bit difficult to see how we’re going to get there in a world with 2 billion smoke-belching vehicles.

In the car-mad U.S., the transportation sector (which also includes planes, trains, and ships) accounts for 28% of all greenhouse gas emissions, second in importance only to energy generation (34%). As developing nations rapidly expand their use of motorized vehicles, their greenhouse-gas profiles will increasingly resemble that of the U.S.

Until recently, diesel engines, which burn fuel more efficiently than petrol engines, have been pushed hard in many nations. However, it’s now understood that diesels, unless operating under optimal conditions, produce large amounts of heat-absorbing soot and toxic nitrogen oxides.

Try Not to Breathe

If you live in a big city, a good survival strategy is to hold your breath. This may not be viable for long periods of time but as a short-term approach it clearly has its benefits.

That’s because motorized vehicles are a massive source of urban air pollution, and especially of nano-particles that have been linked to maladies ranging from increased autoimmune diseases to cardiovascular disease.

Indeed, a 2014 study by the Massachusetts Institute of Technology concluded that, in the U.S., you’re considerably more likely to die from vehicle-related pollutants than from car crashes.

Roads Everywhere?

Possibly the worst impact of all those additional vehicles will be the new roads they require. It’s currently projected that, by 2050, the world will have another 25 million kilometers of paved roads — enough to encircle the planet more than 600 times.

Today, new roads are going virtually everywhere, including many of the world’s last surviving wild places. We build roads to log forests, to extract oil, gas and minerals, to defend our borders, to increase economic growth and trade, and to integrate our economies.

It would be one thing if we’d just build the roads, but they also open up wild areas to a Pandora’s box of environmental ills — ranging from increased wildlife poaching to elevated forest destruction, wildfire, illegal mining, and land speculation.

Globally, the frenetic expansion of roads is probably the single greatest threat to nature. Climate change is eroding ecosystems like an acid, but road expansion is battering away at them like a sledgehammer.

What Are We to Do?

How can we add another billion cars and not cost the Earth? Here are three suggestions.

First, we need to drive smaller, more fuel-efficient vehicles. In Europe, for instance, small and even tiny cars are increasingly the norm. There’s enormous scope for the U.S., Canada, Australia, and many other industrial and developing nations to move in this direction.

Second, we need to get a lot smarter about where we put roads. Roads should be avoided in remaining wilderness, sites with high biodiversity, and protected areas. ALERT researchers have been leading global efforts to map out where on Earth roads should and should not go (see here, here, here, here, here, here, and here), to maximize their social benefits while limiting their environmental costs.

Finally, we need to raise taxes on petroleum and add surcharges for petrol-guzzling vehicles. We can use those proceeds to improve public transportation and amenities such as bicycle lanes. There’s simply no rational reason that one human needs a Chevy pickup exceeding 2,000 kilograms to move around.

The bottom line: Unless we start thinking hard, we’ll soon be living in an increasingly noisy, polluted, and nature-deprived world where the din of 2 billion cars seems far more like a curse than a blessing.

By 2010 the Earth had reached a remarkable milestone: one billion cars — or, to be precise, one billion motorized vehicles, including cars, trucks, buses and motorcycles but excluding off-road vehicles such as tractors and bulldozers. Of course, the overwhelming majority of these are powered by fossil fuels.

And if that figure isn’t jolting enough, by 2030 it’s projected that we will have double that number: 2 billion cars.

What will this mean for our planet, our health, our lifestyles, and our environment?

Traffic Jam

The exponential increase in vehicles is coinciding with the growth of megacities across the world, especially in developing nations. By 2030, more than half of the world’s projected 9 billion people will live in cities, with the total land area engulfed by urbanization expected to triple.

If you think traffic jams are bad now, imagine what it’ll be like in a world with another 2 billion people than we have today — who will be increasingly crammed into crowded urban areas and who will be driving another 1 billion vehicles.

If you’ve ever visited a mega-city like Beijing or São Paulo or Jakarta, you’ll realize that traffic chaos is the norm, not the exception. And that’s even outside of rush hours.

And with more vehicles, traffic accidents will surely increase. The World Health Organization estimates that 1.25 million people are currently killed in vehicle accidents each year. For people ranging from 15 to 29 years of age, it is the number one cause of death.

By 2030, the number of fatalities is expected to rise to 1.8 million people per year. If vehicle-related mortality were considered a global epidemic, it’d be a more important killer than HIV-AIDS.

Greenhouse Gases

At the Paris climate conference, global leaders committed to limit global warming to 2 degrees C, with a stated aspiration to limit the increase to 1.5 degrees C. Not to put too fine a point on it, but it’s a bit difficult to see how we’re going to get there in a world with 2 billion smoke-belching vehicles.

In the car-mad U.S., the transportation sector (which is dominated by motorized vehicles but also includes planes, trains, and ships) accounts for 28% of all greenhouse gas emissions, second in importance only to energy generation (34%). As developing nations rapidly expand their use of motorized vehicles, their greenhouse-gas profiles will increasingly resemble that of the U.S.

Until recently, diesel engines, which burn fuel more efficiently than petrol engines, have been pushed hard in many nations. However, it’s now understood that diesels, unless operating under optimal conditions, produce large amounts of heat-absorbing soot and toxic nitrogen oxides.

In what has evolved into a spectacular global scandal, German manufacturer Volkswagon even tweaked its software to produce falsely low emissions for its diesel cars under test conditions, while belching away on the road.

Try Not to Breathe

If you live in a big city, a good survival strategy is to hold your breath. This may not be viable for long periods of time but as a short-term approach it clearly has its benefits.

That’s because motorized vehicles are a massive source of urban air pollution, and especially of nano-particles that have been linked to maladies ranging from increased autoimmune diseases to cardiovascular disease.

Indeed, a 2014 study by the Massachusetts Institute of Technology concluded that, in the U.S., you’re considerably more likely to die from vehicle-related pollutants than from car crashes.

Roads Everywhere?

Possibly the worst impact of all those additional vehicles will be the new roads they require. It’s currently projected that, by 2050, the world will have another 25 million kilometers of paved roads — enough to encircle the planet more than 600 times.

Today, new roads are going virtually everywhere, including many of the world’s last surviving wild places. We build roads to log forests, to extract oil, gas and minerals, to defend our borders, to increase economic growth and trade, and to integrate our economies.

It would be one thing if we’d just build the roads, but they also open up wild areas to a Pandora’s box of environmental ills — ranging from increased wildlife poaching to elevated forest destruction, wildfire, illegal mining and land speculation.

Globally, the frenetic expansion of roads is probably the single greatest threat to nature. Climate change is eroding ecosystems like an acid, but road expansion is battering away at them like a sledgehammer.

What Are We to Do?

How can we add another billion cars and not cost the Earth? There are not a lot of easy answers but here are three suggestions.

First, we need to drive smaller, more fuel-efficient vehicles. In Europe, for instance, small and even tiny cars are increasingly becoming the norm. There’s enormous scope for the U.S., Australia and many other industrial and developing nations to move in this direction.

Second, we need to get a lot smarter about where we put roads. Roads should be largely verboten in remaining wildernesses, sites with high biodiversity and endangered species, and protected areas. In 2014 ALERT director Bill Laurance led an effort to devise a global roadmap that indicates where roads should and should not go, to maximize their social benefits while limiting their environmental costs.

Finally, we need to raise taxes on petroleum and add surcharges for petrol-guzzling vehicles and use those proceeds to improve public transportation and amenities such as bicycle lanes. There’s simply no sound reason that a single human requires a Chevy pickup exceeding 2,000 kilograms in order to move around.

The bottom line: Unless we start thinking hard, we’ll soon be living in an increasingly noisy, polluted, and nature-deprived world where the din of 2 billion cars seems far more like a curse than a blessing.